Sound detecting device



y 1958 A. M. WIGGINS 233mm SOUND DETECTING DEVICE Filed Dec. 9. 1953 2Sheets-Sheet l May 6, 1%58 A. M. WIGGINS SOUND DETECTING DEVICE 2Sheets-Sheet 2 Filed Dec. 9Q 1953 jfl gwyau 72 3 agwa SOUND DETECTINGnnvrcn Alpha M. Wiggins, Buchanan, Mich., assignor to Electro- Voice,Incorporated, Buchanan, Mich.

Application December 9, 1953, Serial No. 397,077

10 Claims. (Cl. 340-8) The present invention relates to devicesresponsive to sound, particularly devices responsive to sound under thesurface of a liquid, such as water.

In the past, underwater sound. has been detected by devices of varioustypes. One type of sound responsive device utilizes a hollow bariumtitanatecylinder with plugs on either end and electrodes on the innerand outer surfaces of the hollow cylinder. The occurrence of soundpressure causes the diameter dimension of the hollow cylinder to changeresulting in the generation of an electrical signal. In such a device,the force operating to change the diameterof the hollow cylinder isequal to the product of the sound pressure and the area of the outersurface of the hollow cylinder. 1

It is an object of the present invention to provide a devicefordetecting sound inwhich the force operating to produce the electricalsignal is greater than the product of the sound pressure and theexternal surface of the electro-rnechanical transducer. In this manner,a device may be provided having the advantage of producing an electricalsignal of greater magnitude with a given electromechanical transducerthan the devices presently known to the art.

It is also an object of the present invention to provide a soundresponsive device in which the size and amount Further, it is an objectof the present invention to A provide a sound responsive device which isparticularly useful for the detection of underwater sounds.

Other objects and advantages of the present invention will becomereadily apparent to the man skilled inthe art from a further reading ofthis specification, particularly when viewed in the light of thedrawings, in which:

Figure 1 is a longitudinalsectional view of a sound detecting deviceconstructed according to the teachings of the present invention;

Figure 2 is a vertical section view taken along line 2-2 of Figure 1;

Figure 3 is a vertical sectional view of another embodiment of thepresent invention;

Figure 4 is a transverse sectional view taken along line 44 of Figure 3;

Figure 5 is a vertical sectional view of another embodiment of thepresent invention;

Figure 6 is a transverse sectional view of another embodiment of thepresent invention; and

Figure 7 is a transverse sectional view of still another embodiment ofthe invention.

In elementary form, a sound detecting device constructed according tothe present invention has at least one electro-mechanical transducerdisposed within a segrnented hollow member in contact with each of thesegments of the member. Figure 1 illustrates such a device utilizingthree electro-mechanical transducers designated 9, which have hollowpiezoelectric cylinders 10 disposed within a much longer pair ofsubstantially semicylindrical members 12 and 14, which for purposes ofsimplicity will be termedsemicylinders although it will be understoodthat a gap is disposed between the members. 7

' One electrode 16 is aflixedtothe inner surface of each hollow cylinder10, and the other electrodelSis aflixed to the outer surface of eachcylinder 10 'and contacts both the cylinder 10 and the semicylinders 12and 14. A pair of plugs 20 and 22 preferably resilient, seal the endsofthe semicylinders 12 and 14, and elastic sealing means 24, such asrubber cement or rubbertape, seals the seams between the semicylindersto make the entire unit watertight. I s

As a result of this construction, the radial force applied to theceramic hollow cylinders 10 is equal to the product of the soundpressure and area of the outside surfaces of the semicylinders 12 and'14 which are at tributable to each hollow'cylinder 10.

In a particular construction of the sound detector, 7

the semicylinders are constructed of" aluminum approximately A; inchthick and have an inner diameter of sound detecting approximately /2inch and a length of approximately 5 feet. The. electro-mechanicaltransducers are con-.

structed with barium titanate cylinders 10 approximately A inch thickand silverelectrodes, the cylinders being spaced from each other .byapproximately 2 inches.

While Figure v1 illustrates a sound detector usingthree-electro-mechanical transducers 9, itwill be understood'that theinvention maybe practiced using one orv more transducers, However, thereisan optimum number of transducers for a segmented cylinder of a givenlength. If the spaces between the transducers becomes too great, thesernicylinders will bend between the transducers with the impact ofsound pressure causing a diminution in response, In like manner, if thespaces are too small between successive transducers, optiumum responsewill not be obtained, since the effective area of the semicylindersworking upon each transducer will be reduced. The optimum distancebetween transducers depends principally upon the material and thicknessof the semicylinders,-although the distance can be increased forlarger'diameters. Ithasbeen found that the optimum distance betweentransducers for semicylinders constructed of 1 inch thick aluminum isapproximately from to 4 inches for diameters from /2 inch to 4 inches.

The embodiment shown in Figures 3 and 4 permits the use of longersegmented cylindersfor a given transducer surface in contact with thesegmented cylinder without a loss of response. Infthis embodiment, thesound responsive'device has semicylinders, plugs, sealing means andtransducers identical with those shown in Figures 1 and 2, so the samereference numerals will be used for these elements. This embodimentdiffers, however, in that stiffening members 26 are afiixed to eachsemicylinder 12 and 14 between the electro- I mechanical transducers 9.These stifiening members are in the form of solid pieces'and are affixedto the surface of the semicylinders 12 and 14 on a longitudinal axisequidistant from the seams ofthe segmented, cylinder. I

The stifiening members 26 prevent bending of the semicylinders 12 and 14between successive transducers 9,

and thus permit the use of larger spaces between transducers with anincrease in response, rather than a loss Patented May 6, 1958 ited bythe foregoing disclosure, but rather only by the and'2 have been usedtodesignatetheseelements. The plates 30 and 32 are slightly smaller indiameter than the discs 28, so that pressure" from the semi-cylindersand' l tvvill beexrted iip oif tliedisbd 285' Theflec't'r ddesf meyats'a formed by plating or sp'itteiiiig 'the ses 28 with electricallyconducting material,- suchf silver; one (if advantages thisconstructiofiis' that 'presf' sure from the semicylinders 12 and 14exertedjuia'c'ir'i the aieieelectfic material noi'niaI tothe electricfield; mast-mate" ls eX-liibit the greatest sensitivity urldeithesecoiiditions,pparticularly bariu'rn titanate'; v p w FignrEG illustrates'a sound detectin'gdevicecohstriic'ted accc'irding tattle presentinvelntion vvhic utilize t isa sta t i e w i fi h are'fldisposeds'egtne'nted cylinderidetitlcalin' constfnetiolfwitli't i s ie fn' dtieejl the same ef eren ntimeral s usedto iidsigfilt 11mg: 36 disposedthe deanananwmcn is 6vided 'vi i'tli segment 33* sweetie ma erial; Aea211s wanna r inid.

g 36;.is incontact" with the two semitra fisdu cerfslinay be' ofconstruction knovvn to the arL Fiirther', modifications and alternativesyyill I p he inan skil ed in th art from a reading ottlie' presentdisengage, aid for 111 tendedthat the" $6656 offing fir e sjen tnventionbe not liin-' fdlloiivfiiigclairii's What claimediis l. A soundtioii, 2i plurality of longitudinalsegments of a rigid casing, resilientmeansl interp osed between said segments said r 'ent n'ieans saidsegments being confined within the holl ovv casing member in contactwith each ifii. 9fih he li wp in be .v

2. A soun responsive device co rnprising,in combination; epnrj nf pfelongated longitudinal s gments of, a

riia' cylinder r n ie b mY3= b1 r n v e y w the axis" ilier'eof, a pairof resilient circular plugs, the cylingder' ga rfiem's being attached ateach end to a plug and understood that one 6% indie garisr V i i qi didb iel t ytt s clear that the electrical connections from theesgeaavwene icomprising, in cornbina disposed in adjacent relationshipwith each other to form axis'tlieretifleach segn'ient having an endattached to each of the plugs to form a hollow bifiirca'ted cylinder,resilientsealing means located between adjacent edges I of saidsegments, and at least one cylindrical electromechanical transducerdisposed transversely within the cylinder in contact with both segmentsof the cylinder. 4-. A soundresponsive device comprising the elementsol:' claim 3 wherein a plurality of cylindrical electro-meintlte'bifurcated cylinder.

5. Asound responsive device comprising the elements of claim 4' incombination with a plurality of ribs attacked to each ofi'tlie segments"between successive transceihiiiisjin'g' a houew e iinar'ieai member ofbarium mam.

djgei sa d sb'eifi'g'di'spos'e'd along a longitudinal axis of eachsegment.

6. A sea-ad responsive device comprising the elements of claim 3including an electron-mechanical transducer ate',"anda' p"air ofelectrodes, one electrode being on the oii't'e surface of said memberand the other electrode on.

the inner surfactant said m laise. I W

7. A sound responsivedevice comprising the elements of ,clawhe'r'intlieelonglated substantially semicylindr'ic'al segments. areconstructed of aluminum and said.

segihellit s are' s ealed together by a flexible water seal.

responsive devicecomprising the elements of cla'm 3 including anelectro-mechanical transducer comprisingfa fiat-cylindrical disc ofbarium titanate', and

a pai r of elcti'odes, one ofsaid electrodes being disposed on each ofthe flat sides of the disc.

9.,A soundresponsive device comprising, in combination,, apairpfresilient cylindrical plugs, a pair of elongated substantiallysemicylindrical rigid metal segments;

having an end attached-to each of the plugs to form a hollow bifurcatedcylinder,- resilient means interconnect ing the adjacent edges of saidsemicylindrical segments, at :least one piezoelectricelement attachedbetween the two segments, and a pair of electrodes disposedupon parallelsurfaces of each element.

1Q;- Asound-responsive device comprising the elements ofclaim 3whereinan electro-mechanical transducer corn prises aringhavin'gasegment of a magneto-strictive inaterial' anda secondvsegment ofmagnetically polarized materiaL- and arigelectrical' coil'wound aboutthe ring,

saidringand coil being snugly disposed within and atr tached to thesemicylinders.

"ii'eierime's Cited the file of this patent UNITED STATES PATENTS

